What is Port
In computer networking, a port is an endpoint of communication in an operating system, which identifies a specific process or a type of network service running on that system.
[From Wikipedia, the free encyclopedia]
Every network service on your server uses its own port. HTTP-service (that is responsible for your website functionality) generally uses port 80, so when someone enters URL of your website, e.g. http://appsitedown.com, his/her browser adds :80 and try to establish connection to http://appsitedown.com:80.
HTTP Status Text is a textual reason phrase (such as "Not Found") in the first line of the HTTP response (the status line) that describes the numeric status code.
The most common ports
Here is the list of the most common ports. These are default values, that can be reassigned, redefined or reconfigured on your server.
20/21 - FTP - File Transfer Protocol to upload and download files.
22 - SSH - Secure Shell to connect to the command-line of your server.
25 - SMTP - Simple Mail Transfer Protocol to send emails.
80 - HTTP - Hypertext Transfer Protocol to maintain http:// websites.
110 - POP3 - Post Office Protocol to receive emails.
143 - IMAP - Internet Message Access Protocol to send and receive emails.
161 - SNMP - Simple Network Management Protocol to send SNMP-Traps
443 - HTTPS - HTTP over SSL/TLS (HTTP Secure) to maintain https:// websites.
So what's the problem?
The port unavailability on your server = the service unavailability for your customers.
Here are several possible reasons of unexpected outage of the service and port unavailability:
- ISP (Internet Service Provider) problems;
- service software updates;
- firewall reconfiguration;
- network router reconfiguration;
- and many more.
What is your approach?
Distributed availability monitoring and real-time notifications.
AppSiteDown checks the availability of mission-critical ports of your server from different places over the world, so you could be confident the service is accessible for your customers globally.
Port monitoring is not available by default, but we are ready to setup it for you withing our Custom Check offer.